I have. Honestly when you're trying to get rid of something and an offer that is much better than what you are looking for comes up, I'd feel dumb not taking it, even if the technique seems a little douchey. I don't mean anything personal by it, business is just business.
I suppose that's a little different. In this case, the kid is trying to sell something (a key) and everyone is salivating and has a fucking hard on to see who can get to trade him the fastest and get the key for the lowest amount.